linux-kernel - Re: [PATCH] vhost-net: switch to smp barriers

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Message-ID: <4B6E8E3E.30705@redhat.com>
Date:	Sun, 07 Feb 2010 11:56:14 +0200
From:	Avi Kivity <avi@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
CC:	Rusty Russell <rusty@...tcorp.com.au>, kvm@...r.kernel.org,
	virtualization@...ts.osdl.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, David Miller <davem@...emloft.net>
Subject: Re: [PATCH] vhost-net: switch to smp barriers

On 02/07/2010 11:44 AM, Michael S. Tsirkin wrote:
> On Sun, Feb 07, 2010 at 11:42:29AM +0200, Avi Kivity wrote:
>    
>> On 02/01/2010 07:21 PM, Michael S. Tsirkin wrote:
>>      
>>> vhost-net only uses memory barriers to control SMP effects
>>> (communication with userspace potentially running on a different CPU),
>>> so it should use SMP barriers and not mandatory barriers for memory
>>> access ordering, as suggested by Documentation/memory-barriers.txt
>>>
>>>
>>>        
>> A UP guest running on an SMP host still needs those barriers.
>>      
> Correct. And since vhost net is running host-side, smp_XX
> barriers will do exactly the right thing, right?
>    

Right, of course.  Mixed up virtio and vhost.

-- 
error compiling committee.c: too many arguments to function

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